1. Field of the Invention
This invention relates to binder seals or reinforcing and finishing strips applied to slide fastener tapes, for example, the bottom ends of separating slide fasteners.
2. Description of the Prior Art
One prior binder seal applied to the bottom ends of separating slide fasteners employs a strip woven from greige nylon filament. The woven strip is dyed to a color closely matching the tapes of the slide fastener. A solvent-base adhesive is applied to one side of the dyed strip by means of a doctor blade. Subsequently the strip is folded longitudinally with the adhesive inside and the bottom ends of the slide fastener tapes are inserted within the fold of the strip. While the adhesive is softened by solvent, the folded halves of the strip are bonded by pressure to the opposite sides of the bottom ends of the slide fastener tapes. The bonded strip is then trimmed. This prior art process, besides requiring the steps of weaving and dyeing as well as the relatively difficult step of applying the adhesive by a doctor blade to the woven tape, also requires drying steps to permit the solvent to evaporate. Also inventories of various colored strips must be maintained so that the ends of slide fasteners may be bound without undue delay after manufacture.
U.S. Pat. No. 2,438,615, No. 2,582,456, No. 3,503,102 No. 3,507,013 and No. 4,023,241 disclose slide fasteners with reinforcing strips bonded on the end or other portions of the tapes or stringers. Although the prior art contains the suggestion such as in the above U.S. Pat. No. 3,503,102 for utilizing a plastic film folded around the marginal edges of the tapes of a slide fastener, a reliable and adequate plastic film replacement for the woven tape and solvent adhesive has previously not been found. In the above U.S. Pat. No. 2,582,456 it is described that the amount of heat and pressure applied is important for reason that the plastic material should not be heated to its melting temperature, but merely sufficient to force the strip material into the interstices in the outer surface of the tape so that the strip lies substantially in the plane thereof and so that the tape end has substantially the same thickness as the remainder of the tape. However such prior art plastic strip materials applied by heat and pressure in the prior art were deficient in that the bonds between the strip and the slide fastener tapes were subject to failure during laundry, and often resulted in extruded plastic on the sides of the tape rendering subsequent handling and trimming steps more difficult.